One shot of an RSV vaccine protects adults ages 60 or older from RSV-associated hospitalization and critical illness during two consecutive RSV seasons, according to a study published in JAMA today by the IVY Network research group.
RSV causes substantial seasonal illness during fall and winter in the U.S., with an estimated 100,000-150,000 hospitalizations and 4,000-8,000 deaths occurring annually among adults 60 or older.
The results reinforce the recommendations for RSV vaccines in older adults and lay the groundwork for understanding how long a single dose of the vaccine may be effective, according to Wesley Self, MD, MPH, principal investigator for the IVY Network and Senior Vice President for Clinical Research at Vanderbilt University Medical Center.
"These results clearly demonstrate that the RSV vaccines prevent hospitalizations and critical illness due to RSV infection among older Americans," Self said. "It is exciting to see the public health benefits of this new vaccination program."
Investigators used data from a multicenter hospital network known as the IVY Network (The Investigating Respiratory Viruses in the Acutely Ill Network) to assess RSV vaccine effectiveness. They used a test-negative, case-control study design among 6,958 persons 60 years or older who had been hospitalized with acute respiratory illness at one of 26 hospitals in 20 US states during two RSV seasons from October 1, 2023–March 31, 2024 and October 1, 2024–April 30, 2025.
Overall, vaccination reduced the risk of RSV hospitalization by 58% during two RSV seasons, including 69% in the first year after vaccination and 48% in the second year after vaccination.
"Our data show that the beneficial effects of RSV vaccines appear to wane over time," Self said. "Redosing the vaccine at some interval after the initial dose could be a strategy to maintain protection over longer periods of time. It will be important to continue to closely monitor vaccine effectiveness over time to understand how long the benefit lasts after a single dose and if repeat dosing should be considered."
Current RSV vaccine recommendations are for all adults aged 75 years and older and those aged 60-74 years who are at an increased risk of severe RSV.
This study was funded by the U.S. Centers for Disease Control and Prevention (CDC) via award 75D30122C14944.
